package activiti.fiter;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Map;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class JsonpCallbackFilter implements Filter {
	private static Logger log = LoggerFactory.getLogger(JsonpCallbackFilter.class);

	public void init(FilterConfig fConfig) throws ServletException {
	}

	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
			throws IOException, ServletException {
		HttpServletRequest httpRequest = (HttpServletRequest) request;
		HttpServletResponse httpResponse = (HttpServletResponse) response;

		Map<String, String[]> parms = httpRequest.getParameterMap();

		if (parms.containsKey("callback")) {
			if (log.isDebugEnabled()) {
				log.debug("Wrapping response with JSONP callback '" + ((String[]) parms.get("callback"))[0] + "'");
			}
			OutputStream out = httpResponse.getOutputStream();

			GenericResponseWrapper wrapper = new GenericResponseWrapper(httpResponse);

			chain.doFilter(request, wrapper);

			ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
			outputStream.write(new String(((String[]) parms.get("callback"))[0] + "(").getBytes());
			outputStream.write(wrapper.getData());
			outputStream.write(new String(");").getBytes());
			byte[] jsonpResponse = outputStream.toByteArray();

			wrapper.setContentType("text/javascript;charset=UTF-8");
			wrapper.setContentLength(jsonpResponse.length);

			out.write(jsonpResponse);

			out.close();
		} else {
			chain.doFilter(request, response);
		}
	}

	public void destroy() {
	}
}
